The Federal-style townhouse Dr. Tina Alster and Paul Frazer bought in the Georgetown neighborhood of Washington, D.C., was landmarked and historic, but history had not, in fact, treated it kindly. According to local lore, British spies evaded capture here during the War of 1812, the Underground Railroad routed through, and Confederates once hid in the attic—200 years of traffic that took a heavy toll on the details. By the 1960s, what remained of the original interior had succumbed to a gut renovation that left it with dated wallpaper and millwork, and an enclosed sunroom stuck on the back like a caboose. The previous resident, Pulitzer Prize–winning author Herman Wouk, had even built a secret room behind a bookcase, in which the architects found a stool, a telephone, and .45-caliber ammunition.

For the new owners, the compromised interior was actually a plus. “There were no antique floors or venerable hearths to save, and that suited us,” says Alster, an internationally recognized dermatologist and laser surgeon. “We wanted a house with a historic presence, but one we could put our mark on.” Her husband, Frazer, a political-affairs consultant and former Canadian ambassador to the Czech and Slovak Republics, agrees: “There were no redeeming moldings or architectural features, which gave us a creative impetus.”

“With a really good historic house in a historic district, you don’t erase,” says architect Simon Jacobsen, who worked on the renovation with his father, Hugh Newell Jacobsen, in their recently formed partnership. “But if it’s a lousy building, help yourself. Here there was nothing authentic left inside.”

“We basically started over,” says Hugh. “I’ve spent a career abstracting vernacular and historical architecture to get down to the essentials, and since we had a free hand, there was no problem removing all the offending adjectives to make space and to let light into the building.”

Space and light were exactly what Alster and Frazer wanted, but paring down to essentials was easier said than done. A domino effect set in during construction. “When we altered something, it led to altering something else, and we ended up rebuilding 85 percent of the house,” notes Simon. The architects removed the tacked-on sunroom, bringing the house back to its original crisp and succinct form. They repoured the foundation and lowered the floors to give breathing room to the ground level. Years of uneven settlement had caused the brick façades to begin to wave, as if in “a slow-motion earthquake,” says Simon. “We called in a specialist to restore them brick by brick.”

They also terraced the backyard and added a pool, installing a geothermal heating system underneath. This was conspicuous work, and some of the neighbors became alarmed. “When you have a historic property on the corner, everyone is looking,” Alster points out. “Bringing in a big crane, digging holes to China: It looked like we were oil drilling.”

But the Jacobsens were meticulous, consulting original pattern books to replicate period pocket windows and exterior trim and to restore the bright red front door. The neighbors (and various supervisory commissions) were satisfied with the finished project. “We all persevered,” Alster says. “We’re all friends.”

Inside, the Jacobsens emphasized clean lines and pristine walls. “My fingerprints are no moldings or trims,” says Hugh. Curtains would have muddled the spatial clarity, so the architects used louvered shutters at the windows to control and soften the light. Each wall appears detached from the ceiling and floor by a thin, shadowy reveal, which visually transforms the rooms into an ensemble of floating planes, giving the illusion of greater space.

With ambient light reflecting off the white walls, the stage was set for the clients’ fine and decorative arts collection, which ranges through various 20th-century movements, from Art Deco and German Expressionism to modernism. “We collect what we like,” Alster says. “We don’t have anyone buying for us, and we don’t buy art and furniture to match. I think good designs always go well together, whatever decade they’re from.”

The result is a striking mix of the old and new. “It’s a very different space for Georgetown, where most people keep to the vernacular,” Alster says. “We felt like it was rebirth, a rebirth for a historic house.”